target-arm: Signal Underflow when denormal flushed to zero on output

On ARM the architecture mandates that when an output denormal is flushed to
zero we must set the FPSCR UFC (underflow) bit, so map softfloat's
float_flag_output_denormal accordingly.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>

diff --git a/target-arm/helper.c b/target-arm/helper.c
index f07252768a4268dc04ad784fd25e0b2d16ded42f..05b3ccca2d05ffdddb633d2a7ad4ac56679a64d5 100644 (file)
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -2355,7 +2355,7 @@ static inline int vfp_exceptbits_from_host(int host_bits)
         target_bits |= 2;
     if (host_bits & float_flag_overflow)
         target_bits |= 4;
-    if (host_bits & float_flag_underflow)
+    if (host_bits & (float_flag_underflow | float_flag_output_denormal))
         target_bits |= 8;
     if (host_bits & float_flag_inexact)
         target_bits |= 0x10;